[Note: Details of this review of noted differences between fibromyalgia and chronic fatigue syndrome (ME/CFS) unfortunately remain behind a pay wall. However, we know that Dr. Natelson's work at the Pain & Fatigue Study Center involves projects to better characterize and classify CFS & FM. See information on his research projects here. A list of his previous publications involving ME/CFS and fibromyalgia is provided here.]

Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are medically unexplained syndromes that can and often do co-occur. For this reason, some have posited that the two are part of the same somatic syndrome-examples of symptom amplification.

This hypothesis would suggest that few differences exist between the two syndromes.

To evaluate this interpretation, we have searched the literature for articles comparing CFS to FM, reviewing only those articles which report differences between the two.

This review presents data showing differences across a number of parameters - implying that the underlying pathophysiology in CFS may differ from that of FM.

We hope that our review encourages other groups to look for additional differences between CFS and FM.

By continuing to preserve the unique illness definitions of the two syndromes, clinicians will be able to better identify, understand and provide treatment for these individuals.

In my experience with many different people the difference between these is that FM can be a symptom of ME but can also be a symptom of other pathologies, such as spinal stenosis and the spondylo-arthropathies. FM is also often described in M.S. and even SLE.

This presence of FM in various pathologies suggests that Fm is a symptom cluster which depends on:
a primary illness, genetic factors and spinal involvement.

So trying to define the difference between ME and FM is a bit of a straw-man and we certainly won't get far in this endeavour without proper markers in M.E.